Grab the Paint Bucket Tool (G), pick black color and fill the layer mask of Levels with it. Then grab the Brush Tool (B), set the Master Diameter on 250 pixels and lower its Opacity on about 25%. Pick white color and paint dots over the highlighted areas.

Below you can see how your manipulation should look so far.

Step 18 - Adding Butterfly

Download the picture of butterfly listed in the beginning of the tutorial and drag it into your manipulation. Place it on the top of all layers and name it BUTTERFLY.

You need to do two things before actual blending - remove white background and resize it on proper size.

Let's start with removing the background. Grab the Magic Wand Tool (W) and click on white of the background to make a selection of it. Then simply press Delete on your keyboard to remove it.

To resize it go to Edit > Free Transform or simply press Ctrl + T on your keyboard. Set the size similar as on the preview picture and change also rotation of the picture. Hold Ctrl while resizing to keep the same proportion.

Press Enter to apply the changes.

Step 19 - Blending the Butterfly

Butterfly you've just added has only one purpose - to give you the idea of shape where you're adding the broken glass later. Because of that it's better if you see only borders of it and don't be distracted by colors.

To desaturate the butterfly click on its layer (BUTTERFLY) and press Ctrl + U to activate the Hue/Saturation adjustment. Set the value Saturation on -100 to loose all colors.

To blend the butterfly better with the rest of the picture change its Blending Mode from Normal to Overlay. Because of this blending mode you'll see only borders which is ideal for your purpose.

After this step your image should be similar to the one below.

Step 20 - Adding Broken Glass

Creating the butterfly from broken glass is actually very easy. The whole point of it is to find shards which has similar shape as outer border of the butterfly and move them there.

Download photo of broken glass listed in the beginning of the tutorial and drag it into the manipulation. Place it on the top of all layers and name it GLASS.